[Dogfish40]

Originally Posted by troopie

I rarely use the crash dive order but gave it a try as you said with stock just out of curiosity. Worked fine.

Well, I found the workaround at least.
When I order crash dive, I use the C key on the keyboard. What has evidently happened is, over the course of installing MCCD, the new UI and others that change the keyboard commands, using the 'C' key to crash dive is a risk. The 'C' key works fine if I'm on the surface. Why it surfaces the boat at periscope depth is beyond me at this point.
The workaround is just to use the 'Crash dive button' on the HUD. This will crash dive the boat while submerged. I was very preoccupied with the keys because I use them quite a bit instead of always mousing around.
Troopie, I don't know if you used the 'C' key or not, and if you are using some of the same mods. All these things may be required to get this error, but try using the 'C' key while you're at periscope depth and see what happens (if you didn't use the C key.
Danke und Gute Jagd Kamerad.
D40